Electrical control apparatus



Feb. 1, 1944. HUFNAGEL 2,340,752 I ELECTRICAL CONTROL APPARATUS FiledJuly 16, 1941 l 10) PU 11/ Flgl. @f

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INVENTOR Andrew Hufinayel F flzm HIS ATTORNEY Patented Feb. 1, 1944UNITED STATES PATENT OFFICE ELECTRICAL CONTROL APPARATUS AndrewHufnagel, Wilkinsburg, Pa., assignor to The Union Switch & SignalCompany, Swissvale, Pa., a corporation of Pennsylvania Application July16, 1941, Serial No. 402,609

9 Claims. (Cl. 177-353) My invention relates to electrical controlapparatus, and particularly to apparatus for effecting one function whena control circuit is energized by current of one relative polarity andanother function when the control circuit is energized by current of theother relative polarity.

The apparatus of this invention is an improvement on that shown andclaimed in Letters Patent of the United States No. 2,250,214, grantedJuly 22, 1941, to Harry E. Ashworth.

In the Ashworth application there is shown control apparatus employing apolar relay and a biased polar relay energized from a polarized controlcircuit, and arranged so that the biased polar relay checks the polarrelay to insure that it responds to a change in the polarity of theenergy supplied over the control circuit.

The polar relays employed in this apparatus require much less operatingcurrent than the biased polar relays and hence may have windings ofrelatively low resistance when connected in a series circuit. If thewindings of these relays are connected in multiple across the controlcircuit in the manner shown in the Ashworth application, most of theenergy supplied over the control circuit flows through the winding ofthe polar relay and relatively little of the energy flows through thewinding of the biased polar relay. It has been found that if the controlcircuit is very long, too little energy is supplied to the winding ofthe biased polar relay to pick up the contacts of this relay.

It is an object of this invention to provide improved control apparatusof the type described and in which the windings of the polar and biasedpolar relays are connected in series so that the winding of the polarrelay does not divert energy from the biased polar relay, thereby makingoperation of the biased polar relay more positive and also makingpossible operation of this relay over much longer control circuits thanhas heretofore been practicable.

Another object of the invention is to provide improved control apparatusof the type described which is arranged so that the winding of the polarrelay is maintained energized during movement of the contacts of therelay from one position to the other to thereby insure that on a changein the polarity of the energy supplied to the relay the contacts of therelay will complete their movement from one position to the other.

A further object of the invention is to provide improved controlapparatus of the type described which is arranged to include a snubbingcircuit by delay release of the contacts of this relay so that whencoded energy in which the energy impulses are relatively short issupplied over the line circuit, release of the contacts of the biasedpolar relay will be delayed so that the picked-up and released periodsof the relay contacts are rendered substantially equal in length.

Another object of the invention is to provide improved control apparatushaving a polar relay energized over a control circuit, an auxiliaryrelay associated with the polar relay and energized from the controlcircuit over connections governed by contacts of the polar relay andhaving means efi'ective on a change in the polarity of the energysupplied to the control circuit to maintain the contacts of theauxiliary relay picked up during movement of the contacts of the polarrelay from one position to the other.

Other objects of the invention and features of novelty will be apparentfrom the following description taken in connection with the accompanyingdrawing.

I shall describe three forms of control apparatus embodying myinvention, and shall then point out the novel features thereof inclaims.

In the drawing Fig. 1 is a diagram illustrating one embodiment of myinvention energized over a control circuit employing steady energy.

Fig. 2 is a diagram illustrating a modification of my inventionenergized over a control circuit employing coded energy, and

Fig. 3 is a diagram illustrating the modification of Fig. 2 energizedover a control circuit employing steady energy to provide theequivalentof a retained neutral polar relay.

Similar reference characters refer to similar parts in each of the threeviews.

Referring to Fig. 1 of the drawing, the reference character P designatesa polar relay, while the reference character N designates an auxiliaryrelay. The windings of th relays P and N areenergized over a polarizedcontrol circuit here shown as comprising conductors l0 and II which areconnected by contactsof a pole changer PC with a suitable source ofdirect current, such as a battery the terminals of which are designatedand The conductors l0 and II may be line wires, or they may be the trackrails of a section of railway track, while the pole changer PC may be amanually operated device, it may be the contacts of a relay, or it maybe any other suitable mechanism.

The conductor I0 is connected to polar contact I2 of relay P, whileconductor II is connected to for the winding of the biased polar relayto there one terminal of the winding of relay P. The other terminal ofthe winding of relay P is connected to contact IQ of the relay, Thecontacts l2 and hi control connections for connecting the winding of therelay N in series with the winding of the relay P.

The relay N is of the polar biased type and its contacts become pickedup when and only when energy flows in one direction through the relaywinding. One relay which I may employ is shown in application, SerialNo. 194,160, of Harry E. Ashworth, while another relay which I mayemploy is shown in United States Patent No 2,057,605 issued October 13,1936, to-Herman G; Blosser. The various parts of the. apparatus arearranged so that the relay N picks up only when th positive terminal ofthe source is connected to the left-hand terminal of the relay winding.

A resistance [6 having a resistance substantially greater than that ofthe winding of relay N may be connected across the conductors Ill and II to provide means to maintain energization of the winding of relay P-during movement of the relay contacts from oneposition to the other.

The-contact IT of relay N and contact l8 of relay'P may cooperate toperform any desired control function, as, for example, to control thelamps of a signal S.

When the equipment is in the condition shown in the drawing, energy fromthe positive terminal of the source flows through conductor I I, windingof relay P, and contact [4 of relay P to the left-hand terminal of theWinding of relay N, through this winding, contact 12 of relay P, andconductor It] to the negative terminal of the source. relays P and N areenergized in series, while the polarity of the energy supplied to therelay P is such that the rela contacts occupy their lefthand positionsas shown, and the direction of flow of energy through the winding ofrelay N is that which is effective to pick up the contacts of the relay.Accordingly, contact H of relay N and contact I8 of relay P cooperate toestablish the circuit of the lamp G of signal S.

On a reversa1 of the pole changer PC the positive terminal of the sourceis connected to conductor Ill and the negative terminal of the source isconnected to conductor H. At the instant of reversal of the pole changerPC contacts l2 and M of relay P are in their left-hand positions, asshown, so that energy flows from the positive terminal of the sourceover conductor IE3, and contact 12 of relay P to the right-hand terminalof the winding of relay N, through the relay winding, contact l4 ofrelay P, winding of relay P, and conductor II to the negative terminalof the source.

The energy flowing in this direction through the winding of relay Ntends to cause release of the contact of this relay, while this energyflowing through the Winding of relay P causes the contacts of this relayto move out of engagement with their left-hand contacts and intoengagement with their right-hand contacts;

As soon as the contacts I2 and I4 of relay P move out of engagement withtheir left-hand contacts, the circuit traced above for energizing thewindings of the relays P and N in series is interrupted. Theoperatingcharacteristics of the relay P may be such that the relaycontacts will continue to move subsequent to interruption of the supplyof energy to the relay winding so that the; relay contacts will completetheir movement to-their right-hand position.

When the contacts of relay P complete their Underthese conditions, thewindings of all) movement to their right-hand positions, a circuit icomplete to energize the windings of relays P and N in series, whilethis circuit is arranged so that the positive terminal of the source isconnected to the left-hand terminal of the winding of relay N so thatthe energy supplied to the winding of this relay is efiective to pick upthe relay contacts. In addition, the energy supplied to the winding ofrelay Pis eifective to maintain the contacts of this relay in theirright-hand positions.

As a result of movement of the contacts of relay P from their left-handto their right-hand positions, contact 18 interrupts the circuit of thelamp G of signal S and establishes the circuit of the lamp Y. Thiscircuit includes front contact I! of relay N so that it is establishedonly if relay N is picked up.

The operation of the equipment on a subsequent change in the polarity ofthe energy supplied over the conductors l0 and II is similar to thatdescribed in detail above and will not be repeated.

On interruption of the supply of energy over the conductors l0 and I!contact I! of relay N releases and interrupts the circuit of lamp Y or Gand establishes the circuit of the lamp R.

If, on a change in the polarity of the energy supplied over theconductors I0 and H, the contacts of relay P fail to move from oneposition to the other, the conductors l and I I will be connected to thewinding of relay N in such manner that the positive terminal of thesource is connected to the right-hand terminal of the relay winding.Accordingly, the direction of flow of energy through the winding ofrelay N will be such that the energy is ineffective to pick up the relaycontacts and contact I! will remain released and maintain the circuit ofthe lamp R of signal S. The relay N, therefore, checks response of therealy P to changes in the polarity of the energy supplied over theconductors Hi and I I.

If desired, a resistor l6 may be connected between the contacts l2 and[4 of relay P to provide means to energize the relay P during movementof the relay contacts between their two positions to thereby insure thaton a change in the polarity of the energy supplied to the conductors l0and H the contacts of relay P will complete their movement from oneposition to the other. The resistor 15 is preferably of substantiallyhigher resistance than the winding of relay N so that when the contactsof relay P establish the circuit of the winding of relay N, most of theenergy supplied over the conductors I9 and II is supplied through thewinding of relay N. Because of the high resistance of resistor l5relatively little energy is supplied to the winding of relay P while therelay contacts are in transit. However, after the contacts of relay Phave started their movement, little force is required to cause thecontacts to continue their movement and the energy supplied through theresistance I6 is sufiicient for this purpose.

t will be seen that the arrangement of the control apparatus is suchthat the relay P is connected in series with the winding of the relay N.Accordingly, even if the relay P has a relatively low resistancewinding, it will not divert energy from the relay N, nor will itmaterially reduce th current in the winding of relay N, and sufficientenergy will be supplied to the relay N to operate this relay even thoughthe conductors l0 and I l are relatively long.

Although the modification shown in Fig. l of the drawing has beenillustrated and described in connection with a control circuit inwhichsteady energy is employed, it should be understood that thismodification is adapted for use,

also with a control circuit in which coded or periodically interruptedenergy is employed.

In Fig. 2 of the drawing there is shown a modi fied form of my inventionwhich is particularly adapted for use in signaling systems employingcoded energy in which the energy impulses are relatively short.Signaling systems of the type in which this modification is adapted tobe employed are shown in application Serial No. 393,363 of George W.Baughman, filed May 14, 1941, and in application Serial No. 405,821 ofThomas W. Tizzard, Jr., filed August 7, 1941.

In the systems shown in these applications there is a line circuithaving at opposite ends thereof continuously operating coding devices.The contacts of these devices are operated at different rates and thecontacts of each of the devices control connection from the line wiresto a source of current or to line relays. As the contacts of the codingdevices operate at substantially different rates, there are frequentlyrecurring periods in which the contacts of the coding devices are insuch relationship that energy is supplied from the source at one end ofthe line circuit to the line relays at the other end of the linecircuit. Since the duration of the energy impulses supplied to the linerelays at either end of the line circuit is determined by therelationship of the contacts of coding devices operating at difierentspeeds, these impulses vary in length and some of them may be extremelyshort.

It has been found that some types of decoding apparatus operate mostsatisfactorily if the picked-up and released periods of the codefollowing relays are approximately equal in length. The modificationshown in Fig. 2 provides means to employ the control apparatus of thisinvention in signaling systems of the type described, and to render thecode following relay slow in releasing so that the picked-up periods ofthe relay will be nearly equal in length to the released periods.

The diagram forming Fig. 2 of the drawing shows the line relays andassociated apparatus at one end of the line circuit together with themeans for energizing these relays over the line circuit. As thereinshown, a code transmitter 150T is located at one end of the line wires2!! and 2| and has contacts 23 and 24 which are continuously operatedbetween picked-up andreleased positions at a predetermined rate, such as75 times a minute. The contacts 23 and .24, when picked up, connect thewires and 2| through contacts 25 and 26 of a pole changing device to asource of current.

A code transmitter IBDCT is located at the other end of the line wires20 and 2! and has contacts 28 and 29 which are continuously operatedbetween their picked-up and released positions at a predetermined rate,such as 180 times a minute. The contacts 28 and 29 when released connectthe .line wires 20 and 2| to the windings of line relays P and N inseries.

The relay P is a stick polar relay the contacts of which when moved toeither position remain in that position until energy effective to movethe contacts to their other position is supplied to the relay winding,while the relay N is a biased polar relay similar to the correspondingrelay of the system shown in Fig. 1. The relay P has contacts I2 and Itwhich control the circuit of relay modification shown in Fig. 1. Themodification shown in Fig. 2 differs from that shown in Fig. 1 in that arectifier K is connected across the terminals of the winding of relay Nand is poled is established to supply energy over the line wires 20 and2| to the line relays P and N. When the contacts 25 and 26 of the polechanging device.-

are picked up, the energy supplied over the line wires is of normalpolarity and the contacts I! and M of the relay P occupy their left-handpo-.

sitions as shown, while the positive terminal of the source is connectedto the left-hand termi-' nal of the winding of relay N so that theenergy flows through the winding of relay N in the direction efiectiveto pick up the relay contacts.

As soon as the contacts ofcode transmitter T become released, or thoseof code transmitter IBiICT become picked up, the circuit for supplyingenergy to the relays P and N is interrupted. On interruption of the flowof current in the winding of the relay P the contacts of this relayremain in their left-hand positions because of the stick polarcharacteristic of the relay.

On interruptiono'f the circuit of the relay N- a current is induced inthe-relay winding which tends to flow in the same direction as thecurrent previously present in the relay winding. The rectifier Kprovides a low resistance path for this current so that this currentflows through the winding of relay N and maintains the flux in the relaycore for a time and thereby maintains the contacts of relay N picked upfor a period subse-- quent to interruption of the supply of energy tothe relay. After the expiration of this interval,

a the contacts of relay N release.

On subsequent reestablishment by the contacts of the code transmitters'ISCT and l8IlCT of the circuit for supplying energy over the line wires20 and El to the line relays P and N the contacts of the relay N becomepicked up, while they again become released on interruption of thesupply of energy over the line wires.

As a result of the release and picking up-of the contact 30 of relay N,the two portions of the primary winding of transformer DT arealternately energized and impulses of energy are induced in thesecondary winding of the transformer, while the energy supplied fromthis winding to the winding of relay H is-rectified by the contacts 3!of relay N as explained in United States Patent No. 2,237,788 ,'issuedApril 8.1941,.

to Frank H. Nicholson and Leslie R. Allison.

Because of the snubbing efiect on the relay-N of the circuit includingthe rectifier K the pickedup periods of the contacts of the relay N aresomewhat longer than the impulses of energy supplied to the relay. Thevarious parts are se lected and proportioned so that the snuhbing effectof the rectifier delays the release of the contacts of relay N longenough to make the picked N in the manner explained in connection withthe Accordingly, the contacts of relay N are pickedup periods of thecontacts of relay N approximately equal in length, on the average, tothe released periods of the relay. Accordingly, the impulses of energysupplied from the transformer DT to the relay H when the contacts ofrelay N are in their picked-up position are of substantial magnitude andduration and insure that the energy supplied to the relay H is adequateto keep the relay picked up.

The relay H has a contact 32 which cooperates with contact ll! of relayP to control the circuits of the lamps of signal S. When contact 32 ispicked up and contact I8 is in its normal or lefthand position as shown,the circuit of the lamp G is established.

On release of the contacts 25 and 26 of the pole changing device thepolarity of the energy supplied to the line wires 20 and 2i is reversedand may be considered to be of reverse polarity. At this time energyfrom the positive terminal of the source flows over back contact 26,front contact 24 of code transmitter TECT, line wire 2!, back contact 29of code transmitter IBGCT, contact [2 of relay P, rectifier K, contact Mof relay P, winding of relay P, back contact 28 of code transmitterISUCT, line wire 20, front contact 23 of code transmitter HOT, and backcontact 25 to the negative terminal of the source. The energy suppliedover this circuit to the winding of relay P causes the contacts of thisrelay to shift from their left-hand to their right-hand positions. Therectifier K provides a low resistance path through which energy may besupplied to the relay P so that the winding of relay P is supplied withenergy of relatively high Value. As soon as contacts l2 and I4 becomedisengaged from their left-hand contacts, the circuit for supplyingenergy to the winding of relay P is interrupted, but the relay contactscontinue to move and complete their movement to their right-hand orreverse positions.

When the contacts of relay P are in their reverse positions and energyof reverse polarity is supplied over the line wires, energy is no longersupplied through the rectifier K. Instead the energy flows throughright-hand contact l2 of the relay P to the left-hand terminal of thewinding of relay N, through this winding, righthand contact M of relayP, and thence through the winding of relay P. As soon as the contacts ofrelay P complete their movement to their reverse positions, therefore,the windings of relays P and N are again energized in series, while thedirection of flow of energy through the winding of relay N is the sameas it was before reversal of the polarityof the energy supplied to theline wires and is effective to pick up the relay contacts. In addition,when the contacts of relay P are in their reverse positions, energy nolonger flows through the rectifier K to energize the relay P, while thisrectifier permits energy to flow in the snubbing circuit for relay N asexplained above.

On the supply of coded or periodically interrupted energy over the linewires the contacts of relay N pick up and release so that energy issupplied through the transformer DT to the relay H and contact 32 ofthis relay is picked up. At this time, as contact ill of relay P is inits right-hand position, the circuit of the lamp G is interrupted andthe circuit of the lamp Y is established.

n s sequent pi ng p of the contacts 25 and 26 of the pole changingdevice so that energy of normal polarity is again supplied over the linewires, energy is again supplied through the rectifier K to energize therelay P as long as the contacts of relay P remain in their reversepositions. When the contacts of relay P move to their normal positions,the windings of relays P and N are again energized in series.

If the supply of energy over the line wires is interrupted, relay N willcease to follow code and energy will no longer be supplied through thetransformer DT to the relay H so that contact 32 of relay N will releaseand establish the circuit of the lamp R of signal S.

If on a change in the polarity of the energy supplied over the linewires the contacts of relay P fail to change their position, thepositive terminal of the source will be connected to the righthandterminal of the winding of relay N instead of to the left-hand terminalof this winding. Accordingly, the energy which flows through the windingof relay N will flow in the wrong direction to pick up the relaycontacts and the contacts of the relay will remain released.Furthermore, under these conditions energy may flow freely through therectifier K and little or no energy will flow through the winding ofrelay N so that even if this relay were not of a type responsive toenergy of one polarity only, its contacts would not become picked up.The relay N, therefore. checks operation of the relay P, while therectifier K assists in checking the relay P by preventing energizationof the relay N un less the relay P properly responds to a change in thepolarity of the energy supplied thereto.

The arrangement of relays shown in Fig. 2 of the drawing is not limitedto use where coded energy is employed, but is adapted for use wheresteady energy is employed and when these relays are used in this manner,they operate to provide the equivalent of a retained neutral polarizedrelay. That is, the relays operate so that on a change in the polarityof the energy supplied to them, the contacts of the relay N will remainpicked up while the contacts of relay P change from one position to theother. This is advantageous as it prevents a flash of the lamp R of asignal, which would otherwise be present. Fig. 3 is a diagram showingthis application of the invention,

The apparatus shown in Fig. 3 is substantially the same as that shown inFig. 1 except for the addition of the rectifier K which is connectedbetween the terminals of the winding of the relay N. When the polechanger PC is in the position shown, energy of normal polarity is supplid over the conductors Ill and I! and the windings of the relays P and Nare energized i series. At this time the contacts of the relay P occupytheir left-hand or normal positions, while the positive terminal of thesource is connected to the left-hand terminal of the winding of therelay N. Accordingly, the contact I? of relay N is picked up andcooperates with the contact it of relay P to establish the circuit ofthe lamp G of signal IS.

On a change in the position of the contacts of the pole changing devicePC the supply of energy of normal polarity to the conductors H) and llis interrupted and energy of reverse polarity is supplied thereto. Oninterruption of the supply of energy of normal polarity to theconductors l0 and II and consequent interruption of the flow of energythrough the winding of relay N, a current is induced in this winding andflows freely through the rectifier K so that the contacts of the relayare maintained picked up, as

explained in connection with the modification shown in Fig. 2.

On the supply of energy of reverse polarity to the conductors l0 and Henergy flows from the positive terminal of the source over conductor I0,left-hand contact I2 of relay P, rectifier K, left-hand contact M ofrelay P, winding of relay P, and conductor H to the negative terminal ofthe source. At this time the positive terminal of the source isconnected to the right-hand terminal of the winding of relay N, butsince the resistance of the relay winding is much greater than that ofthe rectifier K little current tends to flow through the relay winding.Furthermore, at this time the induced current is still present in therelay winding and opposes flow of current in the relay winding in thedirection from the right-hand to the left-hand terminal of the relaywinding. Accordingly, little or no current flows through the winding ofrelay N in this direction at this time. This is desirable as currentflowing in this direction would tend to reverse the flux in the relaycore with the result that the relay contacts would become released.

The energy of reverse polarity supplied through the rectifier K to thewinding of relay P causes the contacts of this relay to shift to theirrighthand or reverse positions. As soon as contacts l2 and M becomedisengaged from their lefthand contacts, the circuit traced above forsupplying energy to the winding of relay P is interrupted, but becauseof the operating characteristics of the relay its contacts continue tomove and complete their movement to their righthand or reversepositions. When the relay contacts are in this position, the positiveterminal of the source is again connected to the left-hand terminal ofthe winding of relay N and the relays P and N are energized in series,while the direction of flow of energy through the winding of the relay Nis that which is effective to maintain the contacts of the relay pickedup.

On movement of contact I8 of relay P from its normal to its reverseposition it interrupts the circuit of the lamp G and establishes thecircuit of the lamp Y. As the contact I! of relay N is maintained pickedup during movement of the contacts of relay P between their twopositions, the circuit of the lamp R of signal S is maintainedinterrupted and this lamp is not momentarily lighted.

On subsequent change in the position of the contacts of the polechanging device PC so that energy of normal polarity is supplied to theconductors It! and II the equipment operates substantially as describedand its operation will not be traced in detail.

On interruption of the supply of energy over the conductors l0 and H thecontact I! of relay N becomes released and interrupts the circuits ofthe lamps G or Y and establishes the circuit of the lamp R.

From the foregoing it will be seen that the rectifier K provides asnubbing circuit for the relay N so that the contacts of this relayremain picked up for a period subsequent to interruption of "the supplyof energy to the relay winding. In addition, the rectifier K provides alow resistance path through which energy may be supplied to the Windingof relay P on a change in the polarity of the energy supplied over theconductors I0 and II and prior to a change in the position of thecontacts of the relay P. Since the energy for the relay P may flowthrough the rectifier K, it is not required to flow through the "relaywinding where it would reversethe flux in the relay core and causerelease of therelay to the conductors l0 and H. Accordingly, on a changein the polarity of the energy supplied to the conductors l0 and II thereis no change in the flux in the core of the, relay N and the contacts ofthis relay will remain picked up.

If it is desired to have the relay N check the relay P, the relayNshould be of the polar biased type so that its contacts will pick uponly when energy flows in the proper direction through the relaywinding. However, if it is not necessary to check the relay P, or if therelay P is of a safety type which does not require checking, the relay Nmay be a neutral relay, and it may be provided with a copper ferrule orother means in addition to the snubbing circuit including the rectifierK to render it slow in releasing.

Although the modifications shown in Figs. 2 and 3 have been illustratedand described as employing a relay P the contacts of which will continueto move subsequent to interruption of the supply of energy to the relaywinding so as to ,complete their movement from one position to.energysupplied to the relay, it should be understood that thesemodifications may be provided with a resistor connected between thecontacts of the relay P as shown, in Fig. 1 to maintain the relaywinding energized during movement of the relay contacts between theirtwo positions. I

Although I have herein illustrated and described only three forms ofcontrol apparatus embodying my invention, it is understood that variouschanges and modifications may be made therein within the scope of theappended claims without departing from the spirit and scope of myinvention.

Having thus described my invention, what I claim is: I

1. In combination, a control circuit comprising a first and a secondconductor, means for at times supplying energy of one polarity and atother times supplying energy of the other polarity to said conductors, apolar relay having one terminal of its winding connected to said firstconductor, an auxiliary relay which picks up when and only when currentflows through the winding thereof in a given direction, said polar relayhaving a, first contact efiective when in one position to connect saidsecond conductor to one terminal of the auxiliary relay winding andeffective when in its other position to connect said second conductor tothe other terminal of the auxiliary relay winding, said polar relayhaving a second contact efiective to connect the other terminal of thewinding of the polar relay to the terminal of'the auxiliary relaywindingfiother than that to which said second conductor is connected,whereby the windings of the polar and auxiliary relays-are energized inseries over said conductors, and whereby on a change in the polarity'ofthe energy supplied to said conductors there is a change in thedirection of fiow of energy through the winding of the polar relaybutinot through the winding of the auxiliaryrelayif the contactsof thepolar relay respond to the change in the direction of flow ofenergy-through th relay windings, rectifier connected across theterminals of'the Winding of the auxiliary relay and poled to provide alow resistance circuit for the flow of energy induced in the relaywinding an interruption of the supply of energy to the relay winding tothereby render the relay slow in releasing, and a circuit controlled bya contact of said auxiliary relay and a contact of said polar relay.

2. In combination, a control circuit comprising a first and a secondconductor, means for at times supplying energy of one polarity and atother times supplying energy of the other polarity to said conductors, apolar relay having one terminal of its winding connected to said firstconductor, an auxiliary relay which picks up when and only when currentflows through the winding thereof in a given direction, means effectivewhen the polar relay contacts are in their normal position to connectthe other terminal of the polar relay Winding to the first terminal ofthe auxiliary relay winding and to connect the second terminal of theauxiliary relay winding to the second conductor, said means beingeffective when the polar relay contacts are in their reverse positionsto connect said other terminal of the polar relay winding to the secondterminal of the auxiliary relay winding and to connect the firstterminal of the auxiliary relay winding to said second conductor,whereby the windings of the polar and auxiliary relays are energized inseries and whereby on a change in the polarity of the energy supplied tosaid conductors there is a change in the direction of fiow of energythrough the winding of the polar relay but not through the winding ofthe auxiliary relay if the contacts of the polar relay respond to thechange in the direction of flow of energy through the relay winding, arectifier connected across the terminals of the winding of the auxiliaryrelay and poled to provide a low resistance circuit for the flow ofenergy induced in the relay winding on interruption of the supply ofenergy to the relay winding to thereby render the relay slow inreleasing, and a circuit controlled by a contact of said auxiliary relayand by a contact of said polar relay.

3. In combination, a control circuit comprising a first and a secondconductor, means for supplying over said control circuit coded energycomprising relatively short energy impulses which are separated byrelatively long intervals during which no energy is supplied, the energysupplied to said control circuit being of normal polarity at times andbeing of reverse polarity at other times, a polar relay having oneterminal of its winding connected to said first conductor, a codefollowing auxiliary relay which picks up when and only when currentflows through the winding thereof in a given direction, said polar relayhaving a first contact efiective when in its normal position to connectthe other terminal of the polar relay Winding to the first terminal ofthe auxiliary relay winding and having a second contact efiective whenin its normal position to connect the second terminal of the auxiliaryrelay winding to the second conductor, said polar relay first contactbeing effective when in its reverse position to connect the otherterminal of the polar relay winding to the second terminal of theauxiliary relay winding and the polar relay second contact beingefiective when in its reverse position to connect the second conductorto the first terminal of the auxiliary relay winding, whereby thewindings of the polar and auxiliary relays are energized in series andwhereby on a change in th polarity of the energy supplied to said con'ductors there is a change in the direction of flow of energy through thewinding of the polar relay but not through the winding of the auxiliaryrelay if the contacts of the polar relay respond to the change in thedirection of flow of energy through the relay winding, 3, rectifierconnected across the terminals of the winding of the auxiliary relay andpoled to provide a low resistance circuit for flow of energy induced inthe relay winding on interruption of the supply of energy to the relaywinding to thereby render the relay slow in releasing so that the relaycontacts are in their picked-up periods approximately as long as theyare in their released periods, and apparatus governed by code followingoperation of said auxiliary relay and by a contact of said polar re ay.

4. In combination, a control circuit comprising a first and a secondconductor, means for at times supplying energy of one polarity and atother times supplying energy of the other polarity to said conductors, apolar relay having one terminal of its winding connected to said firstconductor, an auxiliary relay having contacts which are moved from theirreleased to their picked-up po sitions when the relay winding isenergized, means effective when the polar relay contacts are in theirnormal position to connect the other terminal of the polar relay windingto the first terminal of the auxiliary relay winding and to connect thesecond terminal of the auxiliary relay winding to the second conductor,said means being effective when the polar relay contacts are in theirreverse positions to connect said other terminal of the polar relaywinding to the second terminal of the auxiliary relay winding and toconnect the first terminal of the auxiliary relay winding to said secondconductor, whereby the windings of the polar and auxiliary relays areenergized in series and whereby on a change in the polarity of theenergy supplied to the conductors there is a change in the direction offlow of energy through the winding of the polar relay but not throughthe winding of the auxiliary relay if the contacts of the polar relayrespond to the change in the direction of fiow of energy through therelay winding, a rectifier connected across the terminals of theauxiliary relay'winding and poled to provide a low resistance circuitfor flow of energy induced in the relay winding on interruption of thesupply of energy to the relay winding to thereby render the relay slowin releasing, said rectifier also providing a low resistance circuitthrough which on. a change in the polarity of the energy supplied tosaid conductors and prior to a change in the position of the polar relaycontacts energy may be supplied to the winding of the polar relaywithout flowing through the auxiliary relay winding, whereby on a changein the polarity of the energy supplied to said conductors the contactsof said auxiliary relay remain picked up, and a circuit governed by acontact of said auxiliary relay and by a contact of said polar relay.

5. In combination, a control circuit comprising a first and a secondconductor, means for at times supplying energy of one polarity and atother times supplying energy of the other polarity to said conductors, apolar relay having one terminal of its winding connected to said firstconductor, an auxiliary relay having contacts which are moved from theirreleased to their picked-up positions when the relay winding isenergized, means governed by the contacts of the polar relay forreversibly connecting the terminals of the winding of the auxiliaryrelay to the other terminal of the winding of the polar relay and tosaid second conductor, a rectifier connected across the terminals of theauxiliary relay winding and poled to provide a low resistance circuitfor flow of current induced in the relay winding on interruption of thesupply of energy to the relay Winding to thereby render the relay slowin releasing, said rectifier also providing a low resistance circuitthrough which on a change in the polarity of the energy supplied to saidconductors and prior to a change in the position of the polar relaycontacts energy may be supplied to the winding of the polar relaywithout flowing through the auxiliary relay winding, whereby theauxiliary relay contacts remain picked up on a change in the polarity ofthe energy supplied to said conductors, and a circuit governed by acontact of said auxiliary relay and by a contact of said polar relay.

6. In combination, a pair of control conductors to which energy of onepolarity is supplied at times and to which energy of the other polarityis supplied at other times, a polarized relay having one terminal of itswinding connected to one of said control conductors, an auxiliary relay,an asymmetric unit connected between the terminals of the winding ofsaid auxiliary relay, and means governed by polar contacts of saidpolarized relay for reversibly connecting the auxiliary winding and saidasymmetric unit in multiple between the other terminal of the polarizedrelay winding and the other one of said control conductors.

'7. In combination, a pair of control conductors to which energy of onepolarity is supplied at times and to which energy of the other polarityis supplied at other times, a polarized relay having one terminal of itswinding connected to one of said control conductors, an auxiliary relayhaving normally released contacts which become picked up when and onlywhen energy flows through the relay winding from its first to its secondterminal, an asymmetric unit connected between the terminals of theauxiliary relay winding and poled to permit energy to flow from thesecond to the first terminal of said winding, and means governed bypolar contacts of said polarized relay for reversibly connecting theauxiliary relay winding and said asymmetric unit in multiple between theother terminal of the polarized relay winding and the other one of saidcontrol conductors.

8. In combination, a pair of control conductors to which energy of onepolarity is supplied at times and to which energy of the other polarityis supplied at other times, a polarized relay having one terminal of itswinding connected to one of said control conductors, an auxiliary relay,and means including a polar contact of said polarized relay forreversibly connecting the winding of the auxiliary relay between theother terminal of the winding of the polarized relay and the othercontrol conductor, said means being effective in each position of thecontact of said polarized relay to connect in multiple with the windingof the auxiliary relay and in series with the winding of the polarizedrelay an asymmetric unit poled to permit flow of energy therethroughwhen the position of the polarized relay contact and the polarity of theenergy supplied to said control conductors are out of correspondence.

9. In combination, a first and a second conductor, means for reversiblyconnecting said conductors with a source of direct current, a firstrelay having a contact movable between a first and a second position,said first relay being of a type the contacts of which when in theirfirst position are moved to their second position when and only whenenergy flows through the relay winding from its first to its secondterminal, the first terminal of the winding of said first relay beingconnected to said first conductor, an auxiliary relay, and meansincluding a contact of said first relay for reversibly connecting thewinding of the auxiliary relay between the second terminal of said firstrelay and said second conductor, said means being effective in eachposition of the contact of said first relay to connect in multiple withthe winding of said auxiliary relay and in series withthe winding ofsaid first relay an asymmetric unit poled to permit flow of energytherethrough when the position of said first relay contact and thepolarity of the energy supplied to said control conductors are out ofcorrespondence.

ANDREW HUFNAGEL.

